linux-kernel - Re: [PATCH] ipmi: kcs_bmc: handle devm

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Date:   Tue, 27 Nov 2018 07:36:48 -0600
From:   Corey Minyard <minyard@....org>
To:     Nicholas Mc Guire <hofrat@...dl.org>,
        Haiyue Wang <haiyue.wang@...ux.intel.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        openipmi-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ipmi: kcs_bmc: handle devm_kasprintf() failure case

On 11/21/18 9:08 AM, Nicholas Mc Guire wrote:
> devm_kasprintf() may return NULL if internal allocation failed so this
> assignment is not safe. Moved the error exit path and added the !NULL
> which then allows the devres manager to take care of cleanup.


Added the original author.  This looks correct to me, I've included it, 
but I would
like Haiyue to comment, if possible.

Thanks,

-corey


> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
> Fixes: cd2315d471f4 ("ipmi: kcs_bmc: don't change device name")
> ---
>
> Problem located with experimental coccinelle script
>
> Patch was compile tested with: aspeed_g5_defconfig (implies
> CONFIG_IPMI_KCS_BMC=y)
>
> Patch is against 4.20-rc3 (localversion-next is next-20181121)
>
>   drivers/char/ipmi/kcs_bmc.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/char/ipmi/kcs_bmc.c b/drivers/char/ipmi/kcs_bmc.c
> index e6124bd..86d29d2 100644
> --- a/drivers/char/ipmi/kcs_bmc.c
> +++ b/drivers/char/ipmi/kcs_bmc.c
> @@ -440,12 +440,13 @@ struct kcs_bmc *kcs_bmc_alloc(struct device *dev, int sizeof_priv, u32 channel)
>   	kcs_bmc->data_in = devm_kmalloc(dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
>   	kcs_bmc->data_out = devm_kmalloc(dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
>   	kcs_bmc->kbuffer = devm_kmalloc(dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
> -	if (!kcs_bmc->data_in || !kcs_bmc->data_out || !kcs_bmc->kbuffer)
> -		return NULL;
>   
>   	kcs_bmc->miscdev.minor = MISC_DYNAMIC_MINOR;
>   	kcs_bmc->miscdev.name = devm_kasprintf(dev, GFP_KERNEL, "%s%u",
>   					       DEVICE_NAME, channel);
> +	if (!kcs_bmc->data_in || !kcs_bmc->data_out || !kcs_bmc->kbuffer ||
> +	    !kcs_bmc->miscdev.name)
> +		return NULL;
>   	kcs_bmc->miscdev.fops = &kcs_bmc_fops;
>   
>   	return kcs_bmc;